LT1721CGN#PBF

Overview

The LT1721CGN#PBF is a quad comparator from Analog Devices, housed in a 16-lead narrow plastic SSOP package. It operates on a single supply voltage ranging from 2.7V to 6V. The device features an input common mode range extending from 100mV below ground to 1.2V below the positive rail. Propagation delay is specified at 4.5ns with 20mV overdrive and 7ns with 5mV overdrive. Quiescent supply current is typically 4mA per comparator. Outputs are rail-to-rail CMOS/TTL compatible.

Feature Summary

• Features internal hysteresis for stable operation with slow-moving signals
• Rail-to-rail outputs directly interface with TTL and CMOS logic levels
• Input voltage range extends 100mV below the negative supply rail
• Pinout optimized to minimize parasitic effects by shielding sensitive inputs

Applications

• Crystal oscillator circuits
• High-speed differential line receivers
• Window comparators
• Threshold detectors and discriminators
• Zero-crossing detectors

Procurement Notes

Verify the specific ordering suffix matches the required package type and temperature grade. Confirm RoHS compliance status as indicated in the manufacturer's documentation. Ensure the component is sourced from authorized distributors to guarantee authenticity and traceability. Check for any recent product change notices regarding pinout or electrical specifications before finalizing procurement.

Selection Notes

Select this component when high speed and low power consumption are critical requirements. The quad configuration allows multiple comparison functions within a compact footprint. Verify that the application voltage falls within the 2.7V to 6V operating range. Consider the internal hysteresis limits if external noise filtering is not feasible. Ensure the PCB layout accommodates the specific pinout to maximize performance.

Part Context

This part belongs to the UltraFast comparator family designed for single-supply applications. It shares architectural similarities with the dual LT1720 but offers four independent channels. The technology focuses on minimizing propagation delay while maintaining low quiescent current. It is suitable for space-constrained designs requiring fast response times.

Replacement Considerations

LT1721IGN#PBF: Same quad comparator with extended industrial temperature range (-40°C to 85°C).

FAQ

How does the internal hysteresis affect the input trip points?

Internal hysteresis creates distinct upper and lower trip points, preventing output oscillation when input signals change slowly or contain noise.

What is the behavior of the inputs when they exceed the common mode range?

If both inputs exceed the positive limit, the output polarity becomes random until recovery. Phase reversal protection prevents false inversion down to -400mV common mode.